1. Field of the Invention
The present invention relates to a glass-aluminum nitride composite having a high heat conductivity, particularly a glass-aluminum nitride composite having properties suitable for a semiconductor packaging material.
2. Description of the Prior Art
An increase in the speed of electronics elements and an increase in the integration density have been rapidly advanced. This has led to a severer demand for an insulating substrate on which the elements are mounted and packaging material. A high heat conductivity for coping with an increase in the density of heat buildup, a low dielectric constant for coping with an increase in the speed, and a lowering in the conductor resistance are particularly required of the packaging material. Regarding the highly heat conducive material, development has been made on an AlN material in addition to BeO and SiC. On the other hand, the demand for a lowering in the dielectric constant and a lowering in the conductor resistance cannot be satisfied by the highly heat conductive material, and priority has been given to the development of a glass-ceramic composite material. In the glass-ceramic composite material, both the heat conductivity and the mechanical strengths are so low that no satisfactory properties are obtained. For this reason, in order to meet the demand, studies have been made on a composite material comprising glass and a highly heat conductive powder. For example, Japanese Patent Laid-Open No. 210043/1988 disclosed a composite comprising glass and aluminum nitride powder. This composite has a permittivity of 5 to 7 and a heat conductivity of 20 W/m.K. Further, in Japanese Patent Laid-Open Nos. 221162/1990 and 196073/1990, a further slight improvement in the heat conductivity could be attained by specifying the oxygen content in aluminum nitride.
The above-described conventional glass-aluminum nitride composite is still unsatisfactory not only in the improvement in the heat conductivity but also in the strength of the substrate, and the improvement achieved therewith is at the most that of the performance of the conventional low temperature fired substrate, so that this composite cannot satisfy a further advanced property requirement. In the present invention, the heat conductivity is further improved particularly in a glass composite having a low permittivity and a high heat conductivity and provides a material having a high strength besides the abovedescribed properties.